Carbonylation processes are old in the art as exemplified by U.S. Pat. No. 1,920,373 which discloses the reaction between carbon monoxide and water in the presence of catalytic substances with a zeolitic structure to produce oxygen containing aliphatic compounds. Also well known are the carbonylation processes for the preparation of carboxylic acids from alcohols and especially the production of acetic acid by the carbonylation of methanol.
The prior art teaches the use of a number of catalysts for the synthesis of carboxylic acids by reaction of alcohols with carbon monoxide at elevated temperatures and pressures in both gas phase fixed bed reactions and liquid phase reactions. Catalysts such as phosphoric acid, phosphates, heavy metal salts such as zinc and cuprous chlorides, silicates of various metals, and boron trifluoride in various hydration states have been reported to function for the production of acetic acid by reaction of methyl alcohol and carbon monoxide at elevated temperatures and pressures of the order of 400.degree. C. and 10,000 psig, respectively. Somewhat less severe reaction conditions of temperature and/or pressure have been reported in the literature employing specific catalyst compositions, e.g., 330.degree. to 340.degree. C. using liquid phosphoric acid containing copper phosphate; 300.degree. to 500.degree. C., and 2,000 to 4,000 psig using active charcoal impregnated with phosphoric acid; and 260.degree. to 360.degree. C. and 2,800 to 5,000 psig using metal carbonyls, such as iron, cobalt and nickel, in conjunction with their halides or free halogens in the liquid phase.
In addition, U.S. Pat. No. 2,019,754 discloses the reaction of aliphatic alcohols and carbon monoxide in the vapor phase in the presence of a catalyst which is a gaseous adsorbent, such as the adsorbent oxides of aluminum, silicon, magnesium, titanium, zirconium and tungsten.
U.S. Pat. Nos. 3,689,533 and 3,717,670 are representative of the prior art preparation of carboxylic acids and esters by the reaction of alcohols and carbon monoxide in the presence of a supported catalyst comprising a rhodium component and a halide promoter. Included in the extensive listing of suitable support, or carrier, materials for the rhodium catalyst are "zeolites as well as the zeolitic molecular sieves".
U.S. Pat. No. 4,134,912 discloses the preparation of acetic acid by the carbonylation of methanol using an iodide and a nickel catalyst in the presence of a tin promoter.
CA 93:45920m discloses that NaX zeolite containing 0.2 to 0.5% rhodium promoted with iron, copper, cobalt and nickel oxides catalyzed the preparation of methyl acetate with 90 to 94% selectivity by carbonylating methanol at 180.degree. to 230.degree. and 1 atmosphere.
J. B. Nagy, et al. in J. MOL. CAT., 5 (1979) 393-397 describe the .sup.13 C-nmr investigation of the conversion of methanol, in the presence of carbon monoxide, on H-ZSM-5 zeolite. The methanol was contacted with carbon monoxide at a pressure of 130 torr. It is stated that the presence of carbon monoxide has little effect on the conversion of methanol although some carbon monoxide is incorporated into the products. Carboxylic group containing products were not detected by .sup.13 C-nmr.
C. D. Chang and A. J. Silvestri in J. Cat. 47 (1977) 249-259 describe the conversion of numerous compounds besides methanol to hydrocarbons using ZSM-5 type catalysts. Carbonyl containing compounds including acetone, acetic acid, n-propyl acetate and n-butyl formate were converted.
Currently, the commercially practiced art which uses a rhodium catalyst and a halide promoter for the synthesis of acetic acid from methanol and carbon monoxide has a number of problems and deficiencies. Capital and operating costs due to the use of a homogeneous rhodium catalyst are one example. The use of a rhodium catalyst process necessitates a supply of catalyst makeup in addition to the catalyst charge and also requires catalyst recovery and recycle equipment. The use of an iodide containing promoter in the acetic acid process requires an iodide charge and makeup, and recycle equipment. Additionally, the use of iodide renders the system extremely corrosive requiring expensive and exotic materials of construction. Further, the presence of water in the liquid reaction medium leads to complicated and expensive product separations.
A catalyst which has become increasingly important in numerous catalyzed processes is the crystalline zeolite ZSM-5 disclosed in U.S. Pat. No. 3,702,866. It is well known that ZSM-5 and ZSM-5 type crystalline zeolites are very useful in the conversion of methanol or its derivatives to hydrocarbons, particularly gasoline. Representative of such art are U.S. Pat. Nos. 3,894,106; 3,894,107; 3,928,483; 4,011,278; 4,013,732; 4,066,714; 4,083,888; 4,139,600; and 4,229,422.
C. D. Chang, et al. in J. CATAL. 56 (1979) 169-173, teach that the ZSM-5 type zeolites reversably convert methanol to dimethyl ether as the initial step in the reaction sequence to the production of hydrocarbons.